1. What is nuclear astrophysics?

Why stars shine?

What are the stars made of?

Are stars moving or changing?

L. Gialanella

RIB in experimental Nuclear AstrophysicsLucio Gialanella

Dipartimento di Matematica e Fisica

Seconda Università di Napoli and INFN – Napoli

Naples, Italy

RIB in experimental Nuclear AstrophysicsLucio Gialanella

Dipartimento di Matematica e Fisica

Seconda Università di Napoli and INFN – Napoli

Naples, Italy

1. What is nuclear astrophysics?

Why stars shine?

What are the stars made of?

Are stars moving or changing?

L. Gialanella

1 - Source of stellar energy: gravitational

• The virial theorem describes enegetically the gravitational contraction:

K=-1/2 Ug

K internal energy

Ug= gravitational potential energy

For the Sun:

Ug~ 3G M2/(5R) ~ 4· 10-10 (2 · 1030)2 / (7 · 108) J ~ 2 · 1042 J

L ~ 1.3 ·103 4π/DW ~ 3.8 ·1026 J/s

Ug/(2L) ~ 2.5 ·1015 s ~ 30 My (Kelvin-Helmholtz)

So, gravitation can account for a lifetime of the order of 10 My,

consistent with the (wrong) estimate of Earth’s age (Lord Kelvin’s

estimate)

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Increasing temperature

Credit: http://chandra.harvard.edu/graphics/edu/formal/variable_stars/HR_diagram.jpg

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V. Castellani „Astrofisica stellare“ Zanichelli, 1985

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Luminosity mass relation in MS

Stellar quiescent burning

hydrostatic equilibrium

heat transport

mass continuity

energy conservation

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The Observatory, Vol. 42, p. 371-376 (1919)

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2. Source of stellar energy: nuclear

• Nuclear binding energy per nucleon is BE~ 8MeV

Un= 1.9·1030/1.6·10-27 8 1.6·10-13 J ~ 1.5·1045 J

Un/L ~ 100 Gy

But kT

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Mass gap A=5, 8

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Velocity-Distance Relation among Extra-Galactic Nebulae.

Edwin Hubble PNAS 1929;15:168-173

©1929 by National Academy of Sciences

Hubble’s law (1929)

V=Hd con H=71±7 km s-1 Mpc-11 Mpc=3.1 1019 km H-1=13.8 Gy

Hubble&Humason ApJ 1931

But there was no

way to ovecome

the gap at A=5, 8

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Big Bang Nucleosynthesis

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but stellar nucleosynthesis alone cannot account for the

abundances of light elements

=894±5 s

http://www.astro.ucla.edu/~wright/BBNS.html

Big Bang Nucleosynthesis revised

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since v has a distribution P(v)

if v is the relative velocity

Nuclear reactions in stars

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P(v) -> Maxwell Boltzmann distribution

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Pro

bab

ilit

yd

ensi

ty

energy

Pro

bab

ilit

yd

ensi

ty

energy

P(v) -> Maxwell Boltzmann distributione.g. p+p

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Gamow Peak

Maxwell-BoltzmannP exp(-E/kT) Penetrability

Ps exp(-(Ec/E)1/2)

Pro

bab

ilit

yd

ensi

ty

energy

Pro

bab

ilit

yd

ensi

ty

energy

Same temperature but larger coulomb barrier

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Gamow Peak

Maxwell-Boltzmann exp(-E/kT) Penetrability

Ps exp(-(Ec/E)1/2)

Pro

bab

ilit

yd

ensi

ty

energy

Pro

bab

ilit

yd

ensi

ty

energy

Gamow Peak

Maxwell-Boltzmann exp(-E/kT)

Same Coulomb barrier but higher temperature

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PenetrabilityPs exp(-(Ec/E)

1/2)

Since s is dominated by the penetrability of the coulomb barrier, it isusual to factorize it out and define the S factor

Reaction E0(keV) Integral

p+p 5.9 7 10-6

4He+12C 56 5.9 10-56

16O+16O 237 2.5 10-237

Sun : T6 = 15

So, E0 = f(Z1, Z2, T): that is the reason for separate, subsequent burnings

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p + p 2H + e+ + [0.27 MeV] p + e- + p 2H + [1.44 MeV]

2H + p 3He +

3He + 3He 4He + 2p 3He + 4He 7Be + 3He + p 4He + e+ +

7Be + e- 7Li + [0.81 MeV] 7Be + p 8B +

7Li + p 8Be 8B 8Be + e+ + [6.80 MeV]

8Be 2 4He 8Be 2 4He

H burning (T6 10-60)

99.75% 0.25%

86% 14%

99.89% 0.11%

CHAIN III

Qeff= 19.67 MeV

CHAIN II

Qeff= 25.66 MeV

CHAIN I

Qeff = 26.20 MeV

CHAIN IV

Qeff= 16.84 MeV

pp chain

2·10-5%

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Solar neutrino energy spectrum

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L. Gialanella M. Wiescher et al, ApJ 1989

12C

13N

(p,

61

09

y

14N(p,

1109 y

15O

(p,

21

01

2y

13C

e+

10

m

15N

e+

2 m

CN17F

(p,

17O

e+

64

s

NO

16O

(p,

1108 y

(p,

(p,18F

(p,

18O

e+

10

8 m

(p,

CN

Qeff = 26.02 MeV

NO

Qeff = 25.73 MeV

Hydrogen burning at high temperature and metallicity

CNO bi-cycle CNO cycle

pp chain

Energy generation for pp chain and CNO cycle

Result:

- H burning

- Enrichment in 14N

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Hot CNO (T9~0.1)Stable

Radioactive

Cold

Hot

Break out

12C 15N 16O 18O 20Ne19F

13C 14N 17O 18F 20Na19Ne

13N 15O 17F

14O18Ne

(p,

(p,

(p,

(p,

(p, (p, (p,

(p,(p,

(,

(p,

(,p

(p,

(p,

e+

e+

(p,

(p,

e+

e+

e+ e+

e+ e+(p,

(p,

(p,

I III

II

IV

6109 y

1.1109 y

2.11012 y

2 m

1108 y

10 m

64 s

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Hot NeNa and MgAl cycles (T9~0.1)

20Ne 24Mg(p,

23Na

(p,

(p,

19F(p,

(p,

27Al28Si

(p,(p,

22Na

22Ne

(p,

e+

3 y

r

21Ne

21Na

(p,

e+

22

s

27Si

26Al

26Mg

(p,

e+

6 s

25Mg

25Al

(p,

e+

7 s

(p,

+ other paths (e.g. 21Na(p,)22Mg, 22Mg(p,) 23Al, 23Mg(p,) 24Al

->24Mg)

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26Al Comptel-Integral/SPI

After Hydrogen exhaustion, core contracts

and star expands

So the ashes of

helium burning are

essentially C and O

Helium burningT9~0.1-0.3

Rolfs &Rodney “Cauldron in the cosmos”

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Advanced burnings

Carbon (T9 ~0.6-0.9) 12C+12C

20Ne+ + 4.6 MeV

Neon(T9 ~ 1.2-1.7)

20Ne+(4.7 MeV)->16O+a ;

20Ne+->24Mg+4.6 MeV

20Ne+20Ne->16O+24Mg

23Na+p + 2.2 MeV

23Mg+n - 2.6 MeV

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Oxygen (T9 ~ 1.4-2.3) 16O+16O

28Si++9.6 MeV

31P+p+7.7 MeV

31S+n+1.5 MeV

30Si+2p+0.38 MeV30P+d-2.4 MeV

Silicon (T9 ~ 2.7-4.0) 28Si+

p + A

n

54,56Fe58Ni

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http://hyperphysics.phy-astr.gsu.edu/hbase/nucene/nucbin.html

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V. Castellani „Astrofisica stellare“ Zanichelli, 1985

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HST- NASA, ESA, "Crab Nebula" J. Hester and A. Loll (Arizona State University)

Evolutionary Stages of a 25-M

Star

Stage Core Temperature [K]Core Density

[kg/m3]Duration of Stage

Hydrogen burning

4 107 5 103 7 106 years

Helium burning 2 108 7 105 7 105 years

Carbon burning 6 108 2 108 600 years

Neon burning 1.2 109 4 109 1 year

Oxygen burning 1.5 109 1010 6 months

Silicon burning 2.7 109 3 1010 1 day

Core collapse 5.4 109 3 1012 3 second

Core bounce 2.3 1010 4 1015 milliseconds

Explosion (supernova)

~109 varies 10 seconds

http://www.physics.byu.edu/faculty/christensen

s, r, and p processes

p process

s process

r process

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s process

• low neutron density n ~107-8 n/cm3

• seed from advanced burnings

• neutron sources in burning shells with dredge up :12C(p, )13N(+)13C(,n)16O

14N(,)18F (+)18O(,)22Ne(,n)25Mg

• neutron traps, p.e.14N

• nucleosintesis close to the valley of stability up to A~208

n(A)>(A)

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r-process

- high neutron density n ~1020 n/cm3

- yields depend somwhat on seed nuclei fron advanced burning

- neutron sources: SNII, neutron-star mergers, neutrino-driven winds

following core collapse

- n(A)

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A key feature of r-process: nice movies

http://compact-merger.astro.su.se/movies.html

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httpcompact-merger.astro.su.semovies.html.avi

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Nuclear reactions in the laboratory

X(a,b)Y

Ion beam

target

detectors

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NOTE: s depend on E, and E is not constant through the target

particles in CSRIM calulationwww.srim.org

Reaction yield

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target

particles in CSRIM calulation

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Case of a single resonance

Er=1.4 MeVG=30 keV

DEt=3 to 680 keV)

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resonant+not resonant

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Effective energy for the cross section extracted from a yieldThere are 3 recipes found in the literature

1

2

3

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0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45

0.50

0.55

0.60

0.65

0.70

0.50

0.55

0.60

0.65

0.70

0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45

Ee

ff (

Me

V)

target thickness (MeV)

Ein = 0.660MeV

E_mean

E_median

E_cs

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0.00 0.10 0.20 0.30 0.40

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0.00 0.10 0.20 0.30 0.40 0.50

rate

fra

cti

on

(E

>E

eff

)

target thickness (MeV)

mean

median

cs

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5%

30%

Experimental determination of reaction cross sections

Direct methods:

very low cross sections -> low counting rates

measure outside Gamow window -> extrapolation (reaction mechanism

cosmic radiation + nat. roombckg

Beam/target induced bckg

For RIB: low beam intensity

key improvements: Beams (obvious)

Targets

Detectors

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X(,)Y

Cosmic backgroundNatural radioactivity

No direct natural background

Radiative captures reactions

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0 1000 2000 3000 4000 5000 6000 70000

1000

2000

3000

4000

5000

raw suppressed

Counts

Channel

•4He beam on 12C solid target

•Targets: (low-energy) ion beam implantation

•12C/13C separation of accelerated ions

•Array of Ge detectors

• Eurogam

•Ge surrounded by BGO crystals

(active shielding)

•Compton suppression

•Cosmic ray suppression

compton suppression

Strahl

beam

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M. Fey, PHD Thesis and Assuncao et al.E [MeV]

9.0 9.5 10.0

expected. E = 8.05 MeV

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M. Fey, PHD Thesis and Assuncao et al.E [MeV]

7.5 8.0 8.5

expected. E = 8.05 MeV

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LUNA 1(1992-2001)50 kV

LUNA 2(2000…)400 kV

Laboratory for Underground

Nuclear Astrophysics

Radiation LNGS/surface

Muons

Neutrons

10-6

10-3

LNGS(shielding 4000 m w.e.)

LUNA MV2016->..

LUNA collaboration

1,00E-06

1,00E-05

1,00E-04

1,00E-03

1,00E-02

1,00E-01

1,00E+00

0 2000 4000 6000 8000 10000

E[keV]

coun

ts

1,00E-06

1,00E-05

1,00E-04

1,00E-03

1,00E-02

1,00E-01

1,00E+00

0 2000 4000 6000 8000 10000

E[keV]

coun

ts

3MeV < E < 8MeV: 0.5 Counts/s

3MeV < E < 8MeV0.0002 Counts/s

GOINGUNDERGROUND

HpGe

courtesy LUNA collaboration

-ray detector

Nrecoils = Nprojectiles x ntarget x s x TERNA x Fq x epartNgamma = Nrecoils x e

recoils + “leaky”

beam ions

gas target

accelerated beam ions

beam ions+recoils (10-12-18) Recoil

Mass Separator

Particledetector

RMS : working principle

gate

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Angular and energy broadening by -ray

emission

p = E / c

J = 90° J= 0° / 180°

Full angular broadening Full energy broadening

Recoil Separators

basic principles

Jrecoil

E0

E0 +- DE

DE/E0 ≈ 2 Dp/p = 2E/cprecoil

Jrecoil ≈ tan-1(Dp/p) = tan-1 ( )E/c

precoil

Jmax = 26mrad

-> ø52 mm after 1 m !

DE ~ ±185 keV

E0 = 3.6 MeV

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magnetic dipole

Fz = FL

P

q=rxB

Momentum filter

electric dipole

- +

Fz = Fe

E

q

rxU

2xd=

Energy filter

Wien filter

+

-

Velocity filter

|Fe| = | FL|

v = U

Bxd

Charge insensitive for v=v0

Variable analyzing power

Combine to filteringm

q

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RMS for Nuclear Astrophysicsfor Nuclear Astrophysics

DRAGON

Caltech ARES

ERNA

KUTL

DRS NaBoNA

ERNA

St GEORGE

DRAGON

Caltech ARES

ERNA

KUTL

DRS NaBoNA

DRAGON

ISAC

•Configuration: M-E-M-E•radioactive ion beams•differentially pumped gas target•Acceptances 18mrad (?)•Assumption of FULL acceptances

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20NeARESCaltech

KUTL

DRS NaBoNA

DRAGON ERNA•Configuration: M-W•Target: H containing foil•PARTIAL ACCEPTANCES•Improvements planned toincrease suppression (add. Magnet)

ARESLouvain-la-Neuve

Courtesy of M. Couder, Notre Dame

Calculated acceptancevs reaction kinematics

19Ne

19F

1H(19Ne,)20Na

Needed

calculated

Recoil Separatorsfor Nuclear Astrophysics

DRS

DRAGON

Caltech ARES

ERNA

KUTL

NaBoNA

WF

WF

Target

D

QT

QT

QTFP

DRS

ORNL

•Configuration: W-W-M•Acceptances angle +-45 mrad

energy +-5%

•H-Gastarget(differentially pumped, windowless)

1H(7Be,)8B

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DRAGON

Caltech ARES

ERNA

KUTL

DRS NaBoNA

NaBoNA

Naples1H(7Be,)8B

NaBoNA -> Precursor of ERNA

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Next to come: SECAR at FRIB

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Divergence slits

Object slits

Small beam emittance

-4

-3

-2

-1

0

1

2

3

4

-2 -1 0 1 2

Target collimator

beam

Angular acceptancealong the gas target

Energy acceptance

Change beam energy

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Why is acceptance so important? An example: 12C(,)16O at Ecm=1 MeV

Required acceptance:27 mradActual acceptance: 24 mrad

L. G. and D. Schuermann ENA VI – POS 2011

Recoils 47% 66% 23% Loss (beam and target effects not included)

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Angular acceptance - experimental

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-20 -15 -10 -5 0 5 10 15 200.0

0.2

0.4

0.6

0.8

1.0

tran

smis

sio

n

D E / E0

[ % ]experimental

calculated

Energy acceptance - experimental

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Recoil detection and identificationz

DE Eres

DE·EMZ2

Dt = L (m/2E)1/2

E

Dt

Charge identification

Mass identification

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Recoil detection

DE-ETOF-E

3He(,)7Be

Full acceptance

SuppressionSeparator: 10-10-10-11

Detector : 10-3-10-6

12C(,)16O

3He(,)7Be

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3He(,)7Be – measurements

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3He(,)7Be – measurements

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Adelberger et al 2011

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RecoilMass Separator

detector

ion sources

ion beam analysis and purification

Radio-chemistry 1

2Scatteringchamber

ERNA at CIRCE, Caserta, Italy

- High intensity ion beams- Medium lived RIB- Applied physics- Basic research- Service

NIC XIII – Debrecen - L: GialanellaL. Gialanella

NIC XIII – Debrecen - L: GialanellaL. Gialanella

7Be beam current vs time

NIC XIII – Debrecen - L: Gialanella

HyHydrogen gas target

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NIC XIII – Debrecen - L: Gialanella

0.7-1.0 1019 at/cm2

Hydrogen gas target profile

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7Be beam:109 p/s(up to 1010 p/s)

Five energies600-800 KeV>10% statistics

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Outlook

RIB are an essential tool in Nuclear Astrophysics:

• r-process: half lives, neutron capture far from stability, surrogate reactions

• explosive burnings (novae, supernovae Type I, Xray burst)

p-rich nuclei, low energy

Key experimental issues are:

• beam intensity

• detection apparatuses

I did not present indirect methods, that provide very important information

(e.g. Coulomb excitation, TMH, transfer reactions, and others)

A final remark: new large scale facilities for RIB are promisingly growing,

but stable beams and small facilities are very important in this field.

For questions/comments: lgialanella@na.infn.it

L. Gialanella

References

• D.D. Clayton, „Principles of Stellar Evolution and Nucleosynthesis“,

• Chicago University Press, Chicago, 1968

• C.Rolfs, W.S.Rodney, „Cauldrons in the Cosmos“, Chicago University

• Press, Chicago, 1988

• Ch. Iliadis, „Nuclear Physics of Stars“, Wiley-VCH, Weinheim, 2007

• V. Castellani „Astrofisica stellare“ Zanichelli, 1985

•Very important: all original works

L. Gialanella

One-day SPES Workshop “ Nuclear astrophysics at SPES

November 12th-13th, 2015, Caserta, Italy

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